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<head>
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  <title>Document</title>
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<body>
  
  <script>

    var obj = {
      name: "why",
      age: 18
    }

    // 默认情况下属性都是没有特别的限制
    // obj.name = ""
    // delete obj.name
    // console.log(obj.name)


    // 可以对对象中的属性进行某些限制
    

  </script>

</body>
</html>